Plzzz answer

9. -16

10. 3

11. 4

Step-by-step explanation:

9. 21 = 5 - r

Subtract 5 from both sides;

16 = -r

Divide both sides by -1

-16 = r OR r = -16

10. 8 - 5b = -7

Subtract 8 from both sides;

-5b = -15

Divide both sides by -5

b = 3

11. -10 = 6 - 4m

Subtract 6 from both sides;

-16 = -4m

Divide both sides by -4

4 = m OR m = 4